According to Marx, religion is an expression of material realities and economic injustice. Thus, problems in religion are ultimately problems in society. Religion is not the disease, but merely a symptom. It is used by oppressors to make people feel better about the distress they experience due to being poor and exploited. This is the origin of his comment that religion is the “opium of the masses” - but as shall see, his thoughts are much more complex than commonly portrayed.